Fix: Robust argument parsing for {{call}} syntax to support nested CBS

[nevaeh5379]

PR Checklist

• Have you checked if it works normally in all models? Ignore this if it doesn't use models.
• Have you checked if it works normally in all web, local, and node hosted versions? If it doesn't, have you blocked it in those versions?
• Have you added type definitions?

Description

The Problem

The previous implementation of the {{call::...}} syntax used a simple string.split('::') method to parse its arguments. This had a critical limitation: it could not correctly handle arguments that contained nested CBS (e.g., {{getvar::...}}, {{slot::...}}). This made it impossible to use powerful patterns, such as calling a function with a dynamic value from within an {{#each}} loop.

The Solution

This PR replaces the simple split logic with a more robust, context-aware parser for {{call}} arguments. The new implementation iterates through the argument string while tracking the nesting level of curly braces ({{...}}). As a result, it now correctly identifies :: as a top-level argument separator, while ignoring any :: found inside nested syntaxes.

Key Improvements

• Nested CBS in Arguments: {{call}} can now safely accept other CBS as arguments, enabling dynamic and modular script creation.
• Enhanced Scripting Patterns: This allows for advanced use cases, like using {{#each}} to loop through an array and call a function for each item, as demonstrated below.

Demonstration

The following test case now works as intended.

Test Code:

{{settempvar::my_fruits::{{array::Apple::Banana::Cherry}}}}

{{#func render_item}} 
  <div class="item">
    {{#when::{{arg::1}}::isnot::Banana}}
      - Fruit Name: {{arg::1}}
    {{:else}}
      - This one is a Banana!
    {{/when}}
  </div>
{{/func}}

<div class="fruit-list">
  {{#each {{gettempvar::my_fruits}} fruit}}
    {{call::render_item::{{slot::fruit}}}}
  {{/each}}
</div>

Before:

The parser failed because it incorrectly split the nested {{slot::fruit}} and {{when...}} syntaxes, leading to broken output.

After:

The function is called correctly for each item in the loop, producing the expected HTML structure.